Electric Potential Energy - AP Physics C: Electricity and Magnetism
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What happens to electric potential energy when a charge moves parallel to equipotential?
What happens to electric potential energy when a charge moves parallel to equipotential?
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Remains constant. No work done moving along equipotential surfaces.
Remains constant. No work done moving along equipotential surfaces.
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State the formula for the change in electric potential energy.
State the formula for the change in electric potential energy.
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$\triangle U = q \triangle V$. Change in energy equals charge times change in potential.
$\triangle U = q \triangle V$. Change in energy equals charge times change in potential.
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How does electric potential energy change with distance between two charges?
How does electric potential energy change with distance between two charges?
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Inversely proportional. Energy decreases as $1/r$ when charges move apart.
Inversely proportional. Energy decreases as $1/r$ when charges move apart.
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What is the formula for electric potential energy of a point charge?
What is the formula for electric potential energy of a point charge?
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$U = k_e \frac{q_1 q_2}{r}$. Coulomb's law for potential energy between two point charges.
$U = k_e \frac{q_1 q_2}{r}$. Coulomb's law for potential energy between two point charges.
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Find $U$ if $q = 1,C$, $E = 10,N/C$, $d = 2,m$.
Find $U$ if $q = 1,C$, $E = 10,N/C$, $d = 2,m$.
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$U = -20,J$. Using $U = -qEd = -(1)(10)(2) = -20,J$.
$U = -20,J$. Using $U = -qEd = -(1)(10)(2) = -20,J$.
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What is the relationship between electric potential energy and electric potential?
What is the relationship between electric potential energy and electric potential?
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$U = qV$. Energy equals charge times electric potential.
$U = qV$. Energy equals charge times electric potential.
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What is the relationship between electric potential energy and electric potential?
What is the relationship between electric potential energy and electric potential?
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$U = qV$. Energy equals charge times electric potential.
$U = qV$. Energy equals charge times electric potential.
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What is the formula for electric potential energy of a point charge?
What is the formula for electric potential energy of a point charge?
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$U = k_e \frac{q_1 q_2}{r}$. Coulomb's law for potential energy between two point charges.
$U = k_e \frac{q_1 q_2}{r}$. Coulomb's law for potential energy between two point charges.
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How does electric potential energy change with distance between two charges?
How does electric potential energy change with distance between two charges?
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Inversely proportional. Energy decreases as $1/r$ when charges move apart.
Inversely proportional. Energy decreases as $1/r$ when charges move apart.
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How does electric potential energy relate to the work done by electric forces?
How does electric potential energy relate to the work done by electric forces?
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$W = -\triangle U$. Conservation of energy principle for electric forces.
$W = -\triangle U$. Conservation of energy principle for electric forces.
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What is the effect of doubling the charge on electric potential energy?
What is the effect of doubling the charge on electric potential energy?
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Doubles. Energy scales linearly with charge magnitude.
Doubles. Energy scales linearly with charge magnitude.
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What is the relation of electric potential energy to potential difference?
What is the relation of electric potential energy to potential difference?
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Proportional. Energy changes linearly with potential difference.
Proportional. Energy changes linearly with potential difference.
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Calculate $U$ for $q_1 = 1,C$, $q_2 = 1,C$, $r = 2,m$.
Calculate $U$ for $q_1 = 1,C$, $q_2 = 1,C$, $r = 2,m$.
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$U = 4.5 \times 10^{9},J$. Using $U = k_e\frac{q_1q_2}{r} = (8.99 \times 10^9)\frac{(1)(1)}{2}$.
$U = 4.5 \times 10^{9},J$. Using $U = k_e\frac{q_1q_2}{r} = (8.99 \times 10^9)\frac{(1)(1)}{2}$.
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What happens to electric potential energy as two charges of opposite sign move closer?
What happens to electric potential energy as two charges of opposite sign move closer?
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Decreases. Attractive forces lower potential energy as distance decreases.
Decreases. Attractive forces lower potential energy as distance decreases.
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State the condition for zero electric potential energy between two charges.
State the condition for zero electric potential energy between two charges.
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Infinitely far apart. Reference point where potential energy equals zero.
Infinitely far apart. Reference point where potential energy equals zero.
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Find the change in electric potential energy for $q = 1,C$, $\triangle V = 4,V$.
Find the change in electric potential energy for $q = 1,C$, $\triangle V = 4,V$.
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$\triangle U = 4,J$. Using $\triangle U = q\triangle V = (1)(4) = 4,J$.
$\triangle U = 4,J$. Using $\triangle U = q\triangle V = (1)(4) = 4,J$.
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Calculate the electric potential energy for $q = -3,C$, $V = -2,V$.
Calculate the electric potential energy for $q = -3,C$, $V = -2,V$.
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$U = 6,J$. Using $U = qV = (-3)(-2) = 6,J$.
$U = 6,J$. Using $U = qV = (-3)(-2) = 6,J$.
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What is $\theta$ in the formula for dipole potential energy $U = -pE , \cos \theta$?
What is $\theta$ in the formula for dipole potential energy $U = -pE , \cos \theta$?
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Angle between $\vec{p}$ and $\vec{E}$. Orientation angle between dipole moment and electric field vectors.
Angle between $\vec{p}$ and $\vec{E}$. Orientation angle between dipole moment and electric field vectors.
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Which law is used to calculate the force in electric potential energy formulas?
Which law is used to calculate the force in electric potential energy formulas?
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Coulomb's Law. Foundation for calculating electric forces and energies.
Coulomb's Law. Foundation for calculating electric forces and energies.
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What happens to electric potential energy when two like charges move closer?
What happens to electric potential energy when two like charges move closer?
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Increases. Like charges repel, so moving closer stores more energy.
Increases. Like charges repel, so moving closer stores more energy.
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Which factor does not affect electric potential energy: charge, distance, or color?
Which factor does not affect electric potential energy: charge, distance, or color?
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Color. Physical properties like color don't affect electric interactions.
Color. Physical properties like color don't affect electric interactions.
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Identify the unit of electric potential energy in the SI system.
Identify the unit of electric potential energy in the SI system.
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Joule (J). Standard SI unit for energy in all forms.
Joule (J). Standard SI unit for energy in all forms.
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Calculate electric potential energy for $q_1 = 2,C$, $q_2 = -3,C$, $r = 1,m$.
Calculate electric potential energy for $q_1 = 2,C$, $q_2 = -3,C$, $r = 1,m$.
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$U = -5.4 \times 10^{10},J$. Using $U = k_e\frac{q_1q_2}{r} = (8.99 \times 10^9)\frac{(2)(-3)}{1}$.
$U = -5.4 \times 10^{10},J$. Using $U = k_e\frac{q_1q_2}{r} = (8.99 \times 10^9)\frac{(2)(-3)}{1}$.
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State the constant $k_e$ in the formula for electric potential energy.
State the constant $k_e$ in the formula for electric potential energy.
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$8.99 \times 10^9 , N, m^2/C^2$. Coulomb's constant in SI units.
$8.99 \times 10^9 , N, m^2/C^2$. Coulomb's constant in SI units.
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Identify the symbol for electric potential energy.
Identify the symbol for electric potential energy.
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$U$. Standard symbol for electric potential energy.
$U$. Standard symbol for electric potential energy.
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State how electric potential energy changes with increasing $r$ between two charges.
State how electric potential energy changes with increasing $r$ between two charges.
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Decreases. Inverse relationship between energy and separation distance.
Decreases. Inverse relationship between energy and separation distance.
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Which equation relates electric potential energy to work done by the electric force?
Which equation relates electric potential energy to work done by the electric force?
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$W = -\triangle U$. Work by electric force equals negative change in potential energy.
$W = -\triangle U$. Work by electric force equals negative change in potential energy.
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What is the formula for $U$ in terms of $E$, $q$, and $d$?
What is the formula for $U$ in terms of $E$, $q$, and $d$?
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$U = -qEd$. Standard formula for uniform field potential energy.
$U = -qEd$. Standard formula for uniform field potential energy.
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Calculate electric potential energy for $q = 2,C$, $V = 5,V$.
Calculate electric potential energy for $q = 2,C$, $V = 5,V$.
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$U = 10,J$. Using $U = qV = (2)(5) = 10,J$.
$U = 10,J$. Using $U = qV = (2)(5) = 10,J$.
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How does electric potential energy relate to the work done by electric forces?
How does electric potential energy relate to the work done by electric forces?
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$W = -\triangle U$. Conservation of energy principle for electric forces.
$W = -\triangle U$. Conservation of energy principle for electric forces.
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